This invention relates to an apparatus in which the degree of crowding in an elevator hall is detected by processing data imaged with a television camera.
Heretofore, there has been an apparatus which is adapted to detect the degree of crowding of an elevator hall with waiting persons by the use of a television camera. Such an apparatus for detecting the degree of crowding in the elevator hall having waiting persons is, for example, disclosed in the official gazette of Japanese Patent Application Publication No. 30782/1982, and this prior-art apparatus is shown in FIG. 3.
Referring to FIG. 3, an elevator hall is scanned by a television camera 1, the resulting signal is digitized by an analog-to-digital converter (hereinbelow, termed "A/D converter") 2, and the digital signal is processed in an arithmetic unit 14, thereby to extract a feature in pixel unit.
When no persons are waiting in the elevator hall, the result of the above process is stored in a memory 16. Subsequently, signals in the presence of a waiting person or persons in the elevator hall are stored in a memory 15. The stored contents of the memories 15 and 16 are compared for each pixel by means of a comparator 17, and the output is produced in a case where the corresponding signals of the pixel are different. The number of the non-coincident outputs delivered from the comparator 17 is counted by a counter 18. Accordingly, the content of the counter 18 corresponds to the degree of crowding on each occasion.
The detection accuracy in this case depends greatly upon the brightness of the elevator hall. More specifically, the difference between the presence and absence of at least one waiting person depends upon the difference between the quantities of light entering the television camera, namely, the brightnesses of the elevator hall and can be precisely detected if the difference is great. However, when the difference is small, the detection accuracy decreases. Even with the same illumination equipment, the brightness of the elevator hall changes continuously under the influence of outdoor daylight. In the nighttime, etc., accordingly, the whole elevator hall darkens due to the dark surroundings, and the detection accuracy decreases. Moreover, in a case where the reference data has been set under a bright condition, there is the drawback that, when the whole image darkens, the presence of a waiting person is misrecognized.